Advice needed on RAM disappearing and reverting to single mode

[Beansontoast]

Hi Everyone,

I have a niggle which I am hoping you can help me with.

Basically I have two 8GB sticks of Kingston PC3 rated at PC3-12800.

When I leave everything in BIOS at defaults, I see 16GB available to windows and in the bios it reports that it is dual mode.

All good so far .....

However, I did notiece that it also reports the RAM speed at 1333.

Is this correct?

Should RAM rated as 12800 not be running quicker?
If I manually set to 1666 the RAM reports as only running in single mode, and interestingly enough windows only sees 8GB of the 16GB as available.


Apologies if I have the wrong end of the stick on this one.

Help and some basic advice appreciated.

(ps .. I would paste a screendump of CPU-Z if I could work out how to embed it!)

 

[Beansontoast]

Apologies .... this is on an ASROCK 990FX.
EUFI bios 2.02.1205

 

[Woomack]

Auto/SPD settings will be DDR3-1333 as it's basic profile programmed in your memory. You have to change it manually to 1600 or use XMP profile which has programmed higher settings.
If for some reason XMP won't work then you have to change clock, timings and sometimes also memory voltage manually ( you should have main timings and voltage described on the memory or producer's site ).

 

[Beansontoast]

Thanks Woomack,

Do I have XMP on an ADM rig?

This is an AM3. If not, is it known as something else?

 

[Woomack]

I don't know your board but many AMD boards have it also under XMP. Usually you have memory settings as Auto and when you change it then is also manual or XMP option.
This memory should work without issues if you change only memory clock to 1600. If it won't work then best if you tell what product number has your memory.

 

[redduc900]

I assume you meant DDR3-1600 (200MHz FSB x 8 DRAM multiplier), and not DDR3-1666? If it's reverting to single channel mode, and the OS is only seeing 8 of the 16GB at a DRAM frequency of DDR3-1600, try bumping the CPU NB (default is 1.150V) and/or the NB voltage (default is 1.108V).